/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * A generic kernel FIFO implementation
 *
 * Copyright (C) 2013 Stefani Seibold <stefani@seibold.net>
 */

#ifndef _LINUX_KFIFO_H
#define _LINUX_KFIFO_H

#ifdef __cplusplus
extern "C" {
#endif

/*
 * How to porting drivers to the new generic FIFO API:
 *
 * - Modify the declaration of the "struct kfifo *" object into a
 *   in-place "struct kfifo" object
 * - Init the in-place object with kfifo_alloc() or kfifo_init()
 *   Note: The address of the in-place "struct kfifo" object must be
 *   passed as the first argument to this functions
 * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
 *   into kfifo_out
 * - Replace the use of kfifo_put into kfifo_in_spinlocked and kfifo_get
 *   into kfifo_out_spinlocked
 *   Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
 *   must be passed now to the kfifo_in_spinlocked and kfifo_out_spinlocked
 *   as the last parameter
 * - The formerly __kfifo_* functions are renamed into kfifo_*
 */

/*
 * Note about locking: There is no locking required until only one reader
 * and one writer is using the fifo and no kfifo_reset() will be called.
 * kfifo_reset_out() can be safely used, until it will be only called
 * in the reader thread.
 * For multiple writer and one reader there is only a need to lock the writer.
 * And vice versa for only one writer and multiple reader there is only a need
 * to lock the reader.
 */

#include <linux/compiler_attributes.h>
#include <linux/kernel.h>
// #include <linux/spinlock.h>
#include <stddef.h>
// #include <linux/scatterlist.h>

struct __kfifo {
    unsigned int in;
    unsigned int out;
    unsigned int mask;
    unsigned int esize;
    void *data;
};

#define __STRUCT_KFIFO_COMMON(datatype, recsize, ptrtype) \
    union {                                               \
        struct __kfifo kfifo;                             \
        datatype *type;                                   \
        const datatype *const_type;                       \
        char (*rectype)[recsize];                         \
        ptrtype *ptr;                                     \
        ptrtype const *ptr_const;                         \
    }

#define __STRUCT_KFIFO(type, size, recsize, ptrtype)               \
    {                                                              \
        __STRUCT_KFIFO_COMMON(type, recsize, ptrtype);             \
        type buf[((size < 2) || (size & (size - 1))) ? -1 : size]; \
    }

#define STRUCT_KFIFO(type, size) struct __STRUCT_KFIFO(type, size, 0, type)

#define __STRUCT_KFIFO_PTR(type, recsize, ptrtype)     \
    {                                                  \
        __STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
        type buf[0];                                   \
    }

#define STRUCT_KFIFO_PTR(type) struct __STRUCT_KFIFO_PTR(type, 0, type)

/*
 * define compatibility "struct kfifo" for dynamic allocated fifos
 */
// struct kfifo __STRUCT_KFIFO_PTR(unsigned char, 0, void);

#define STRUCT_KFIFO_REC_1(size) struct __STRUCT_KFIFO(unsigned char, size, 1, void)

#define STRUCT_KFIFO_REC_2(size) struct __STRUCT_KFIFO(unsigned char, size, 2, void)

/*
 * define kfifo_rec types
 */
struct kfifo_rec_ptr_1 __STRUCT_KFIFO_PTR(unsigned char, 1, void);
struct kfifo_rec_ptr_2 __STRUCT_KFIFO_PTR(unsigned char, 2, void);

/*
 * helper macro to distinguish between real in place fifo where the fifo
 * array is a part of the structure and the fifo type where the array is
 * outside of the fifo structure.
 */
#define __is_kfifo_ptr(fifo) (sizeof(*fifo) == sizeof(STRUCT_KFIFO_PTR(typeof(*(fifo)->type))))

/**
 * DECLARE_KFIFO_PTR - macro to declare a fifo pointer object
 * @fifo: name of the declared fifo
 * @type: type of the fifo elements
 */
#define DECLARE_KFIFO_PTR(fifo, type) STRUCT_KFIFO_PTR(type) fifo

/**
 * DECLARE_KFIFO - macro to declare a fifo object
 * @fifo: name of the declared fifo
 * @type: type of the fifo elements
 * @size: the number of elements in the fifo, this must be a power of 2
 */
#define DECLARE_KFIFO(fifo, type, size) STRUCT_KFIFO(type, size) fifo

/**
 * INIT_KFIFO - Initialize a fifo declared by DECLARE_KFIFO
 * @fifo: name of the declared fifo datatype
 */
#define INIT_KFIFO(fifo)                            \
    (void)({                                        \
        typeof(&(fifo)) __tmp = &(fifo);            \
        struct __kfifo *__kfifo = &__tmp->kfifo;    \
        __kfifo->in = 0;                            \
        __kfifo->out = 0;                           \
        __kfifo->mask = ARRAY_SIZE(__tmp->buf) - 1; \
        __kfifo->esize = sizeof(*__tmp->buf);       \
        __kfifo->data = __tmp->buf;                 \
    })

/**
 * DEFINE_KFIFO - macro to define and initialize a fifo
 * @fifo: name of the declared fifo datatype
 * @type: type of the fifo elements
 * @size: the number of elements in the fifo, this must be a power of 2
 *
 * Note: the macro can be used for global and local fifo data type variables.
 */
#define DEFINE_KFIFO(fifo, type, size)                                                               \
    DECLARE_KFIFO(fifo, type, size) = (typeof(fifo)) {                                               \
        {                                                                                            \
            {                                                                                        \
                .in = 0, .out = 0, .mask = ARRAY_SIZE((fifo).buf) - 1, .esize = sizeof(*(fifo).buf), \
                .data = (fifo).buf,                                                                  \
            }                                                                                        \
        }                                                                                            \
    }

static inline unsigned int __must_check __kfifo_uint_must_check_helper(unsigned int val) { return val; }

static inline int __must_check __kfifo_int_must_check_helper(int val) { return val; }

/**
 * kfifo_initialized - Check if the fifo is initialized
 * @fifo: address of the fifo to check
 *
 * Return %true if fifo is initialized, otherwise %false.
 * Assumes the fifo was 0 before.
 */
#define kfifo_initialized(fifo) ((fifo)->kfifo.mask)

/**
 * kfifo_esize - returns the size of the element managed by the fifo
 * @fifo: address of the fifo to be used
 */
#define kfifo_esize(fifo) ((fifo)->kfifo.esize)

/**
 * kfifo_recsize - returns the size of the record length field
 * @fifo: address of the fifo to be used
 */
#define kfifo_recsize(fifo) (sizeof(*(fifo)->rectype))

/**
 * kfifo_size - returns the size of the fifo in elements
 * @fifo: address of the fifo to be used
 */
#define kfifo_size(fifo) ((fifo)->kfifo.mask + 1)

/**
 * kfifo_reset - removes the entire fifo content
 * @fifo: address of the fifo to be used
 *
 * Note: usage of kfifo_reset() is dangerous. It should be only called when the
 * fifo is exclusived locked or when it is secured that no other thread is
 * accessing the fifo.
 */
#define kfifo_reset(fifo)                       \
    (void)({                                    \
        typeof((fifo) + 1) __tmp = (fifo);      \
        __tmp->kfifo.in = __tmp->kfifo.out = 0; \
    })

/**
 * kfifo_reset_out - skip fifo content
 * @fifo: address of the fifo to be used
 *
 * Note: The usage of kfifo_reset_out() is safe until it will be only called
 * from the reader thread and there is only one concurrent reader. Otherwise
 * it is dangerous and must be handled in the same way as kfifo_reset().
 */
#define kfifo_reset_out(fifo)               \
    (void)({                                \
        typeof((fifo) + 1) __tmp = (fifo);  \
        __tmp->kfifo.out = __tmp->kfifo.in; \
    })

/**
 * kfifo_len - returns the number of used elements in the fifo
 * @fifo: address of the fifo to be used
 */
#define kfifo_len(fifo)                       \
    ({                                        \
        typeof((fifo) + 1) __tmpl = (fifo);   \
        __tmpl->kfifo.in - __tmpl->kfifo.out; \
    })

/**
 * kfifo_is_empty - returns true if the fifo is empty
 * @fifo: address of the fifo to be used
 */
#define kfifo_is_empty(fifo)                   \
    ({                                         \
        typeof((fifo) + 1) __tmpq = (fifo);    \
        __tmpq->kfifo.in == __tmpq->kfifo.out; \
    })

/**
 * kfifo_is_empty_spinlocked - returns true if the fifo is empty using
 * a spinlock for locking
 * @fifo: address of the fifo to be used
 * @lock: spinlock to be used for locking
#define kfifo_is_empty_spinlocked(fifo, lock) \
({ \
    unsigned long __flags; \
    bool __ret; \
    spin_lock_irqsave(lock, __flags); \
    __ret = kfifo_is_empty(fifo); \
    spin_unlock_irqrestore(lock, __flags); \
    __ret; \
})
 */

/**
 * kfifo_is_empty_spinlocked_noirqsave  - returns true if the fifo is empty
 * using a spinlock for locking, doesn't disable interrupts
 * @fifo: address of the fifo to be used
 * @lock: spinlock to be used for locking
#define kfifo_is_empty_spinlocked_noirqsave(fifo, lock) \
({ \
    bool __ret; \
    spin_lock(lock); \
    __ret = kfifo_is_empty(fifo); \
    spin_unlock(lock); \
    __ret; \
})
 */

/**
 * kfifo_is_full - returns true if the fifo is full
 * @fifo: address of the fifo to be used
 */
#define kfifo_is_full(fifo)                     \
    ({                                          \
        typeof((fifo) + 1) __tmpq = (fifo);     \
        kfifo_len(__tmpq) > __tmpq->kfifo.mask; \
    })

/**
 * kfifo_avail - returns the number of unused elements in the fifo
 * @fifo: address of the fifo to be used
 */
#define kfifo_avail(fifo)                                                                                     \
    __kfifo_uint_must_check_helper(({                                                                         \
        typeof((fifo) + 1) __tmpq = (fifo);                                                                   \
        const size_t __recsize = sizeof(*__tmpq->rectype);                                                    \
        unsigned int __avail = kfifo_size(__tmpq) - kfifo_len(__tmpq);                                        \
        (__recsize) ? ((__avail <= __recsize) ? 0 : __kfifo_max_r(__avail - __recsize, __recsize)) : __avail; \
    }))

/**
 * kfifo_skip - skip output data
 * @fifo: address of the fifo to be used
 */
#define kfifo_skip(fifo)                                  \
    (void)({                                              \
        typeof((fifo) + 1) __tmp = (fifo);                \
        const size_t __recsize = sizeof(*__tmp->rectype); \
        struct __kfifo *__kfifo = &__tmp->kfifo;          \
        if (__recsize)                                    \
            __kfifo_skip_r(__kfifo, __recsize);           \
        else                                              \
            __kfifo->out++;                               \
    })

/**
 * kfifo_peek_len - gets the size of the next fifo record
 * @fifo: address of the fifo to be used
 *
 * This function returns the size of the next fifo record in number of bytes.
 */
#define kfifo_peek_len(fifo)                                                                        \
    __kfifo_uint_must_check_helper(({                                                               \
        typeof((fifo) + 1) __tmp = (fifo);                                                          \
        const size_t __recsize = sizeof(*__tmp->rectype);                                           \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                                    \
        (!__recsize) ? kfifo_len(__tmp) * sizeof(*__tmp->type) : __kfifo_len_r(__kfifo, __recsize); \
    }))

/**
 * kfifo_init - initialize a fifo using a preallocated buffer
 * @fifo: the fifo to assign the buffer
 * @buffer: the preallocated buffer to be used
 * @size: the size of the internal buffer, this have to be a power of 2
 *
 * This macro initializes a fifo using a preallocated buffer.
 *
 * The number of elements will be rounded-up to a power of 2.
 * Return 0 if no error, otherwise an error code.
 */
#define kfifo_init(fifo, buffer, size)           \
    ({                                           \
        typeof((fifo) + 1) __tmp = (fifo);       \
        struct __kfifo *__kfifo = &__tmp->kfifo; \
        -EINVAL;                                 \
    })

/**
 * kfifo_put - put data into the fifo
 * @fifo: address of the fifo to be used
 * @val: the data to be added
 *
 * This macro copies the given value into the fifo.
 * It returns 0 if the fifo was full. Otherwise it returns the number
 * processed elements.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_put(fifo, val)                                                            \
    ({                                                                                  \
        typeof((fifo) + 1) __tmp = (fifo);                                              \
        typeof(*__tmp->const_type) __val = (val);                                       \
        unsigned int __ret;                                                             \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                        \
        __ret = !kfifo_is_full(__tmp);                                                  \
        if (__ret) {                                                                    \
            __tmp->buf[__kfifo->in & __tmp->kfifo.mask] = *(typeof(__tmp->type))&__val; \
            __kfifo->in++;                                                              \
        }                                                                               \
        __ret;                                                                          \
    })

/**
 * kfifo_get - get data from the fifo
 * @fifo: address of the fifo to be used
 * @val: address where to store the data
 *
 * This macro reads the data from the fifo.
 * It returns 0 if the fifo was empty. Otherwise it returns the number
 * processed elements.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_get(fifo, val)                                                            \
    __kfifo_uint_must_check_helper(({                                                   \
        typeof((fifo) + 1) __tmp = (fifo);                                              \
        typeof(__tmp->ptr) __val = (val);                                               \
        unsigned int __ret;                                                             \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                        \
        __ret = !kfifo_is_empty(__tmp);                                                 \
        if (__ret) {                                                                    \
            *(typeof(__tmp->type))__val = __tmp->buf[__kfifo->out & __tmp->kfifo.mask]; \
            __kfifo->out++;                                                             \
        }                                                                               \
        __ret;                                                                          \
    }))

/**
 * kfifo_peek - get data from the fifo without removing
 * @fifo: address of the fifo to be used
 * @val: address where to store the data
 *
 * This reads the data from the fifo without removing it from the fifo.
 * It returns 0 if the fifo was empty. Otherwise it returns the number
 * processed elements.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_peek(fifo, val)                                                               \
    __kfifo_uint_must_check_helper(({                                                       \
        typeof((fifo) + 1) __tmp = (fifo);                                                  \
        typeof(__tmp->ptr) __val = (val);                                                   \
        unsigned int __ret;                                                                 \
        const size_t __recsize = sizeof(*__tmp->rectype);                                   \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                            \
        if (__recsize)                                                                      \
            __ret = __kfifo_out_peek_r(__kfifo, __val, sizeof(*__val), __recsize);          \
        else {                                                                              \
            __ret = !kfifo_is_empty(__tmp);                                                 \
            if (__ret) {                                                                    \
                *(typeof(__tmp->type))__val = __tmp->buf[__kfifo->out & __tmp->kfifo.mask]; \
                smp_wmb();                                                                  \
            }                                                                               \
        }                                                                                   \
        __ret;                                                                              \
    }))

/**
 * kfifo_in - put data into the fifo
 * @fifo: address of the fifo to be used
 * @buf: the data to be added
 * @n: number of elements to be added
 *
 * This macro copies the given buffer into the fifo and returns the
 * number of copied elements.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_in(fifo, buf, n)                   \
    ({                                           \
        typeof((fifo) + 1) __tmp = (fifo);       \
        typeof(__tmp->ptr_const) __buf = (buf);  \
        unsigned long __n = (n);                 \
        struct __kfifo *__kfifo = &__tmp->kfifo; \
        __kfifo_in(__kfifo, __buf, __n);         \
    })

/**
 * kfifo_in_spinlocked - put data into the fifo using a spinlock for locking
 * @fifo: address of the fifo to be used
 * @buf: the data to be added
 * @n: number of elements to be added
 * @lock: pointer to the spinlock to use for locking
 *
 * This macro copies the given values buffer into the fifo and returns the
 * number of copied elements.
 */
#define kfifo_in_spinlocked(fifo, buf, n, lock) \
    ({                                          \
        unsigned long __flags;                  \
        unsigned int __ret;                     \
        spin_lock_irqsave(lock, __flags);       \
        __ret = kfifo_in(fifo, buf, n);         \
        spin_unlock_irqrestore(lock, __flags);  \
        __ret;                                  \
    })

/**
 * kfifo_in_spinlocked_noirqsave - put data into fifo using a spinlock for
 * locking, don't disable interrupts
 * @fifo: address of the fifo to be used
 * @buf: the data to be added
 * @n: number of elements to be added
 * @lock: pointer to the spinlock to use for locking
 *
 * This is a variant of kfifo_in_spinlocked() but uses spin_lock/unlock()
 * for locking and doesn't disable interrupts.
 */
#define kfifo_in_spinlocked_noirqsave(fifo, buf, n, lock) \
    ({                                                    \
        unsigned int __ret;                               \
        spin_lock(lock);                                  \
        __ret = kfifo_in(fifo, buf, n);                   \
        spin_unlock(lock);                                \
        __ret;                                            \
    })

/* alias for kfifo_in_spinlocked, will be removed in a future release */
#define kfifo_in_locked(fifo, buf, n, lock) kfifo_in_spinlocked(fifo, buf, n, lock)

/**
 * kfifo_out - get data from the fifo
 * @fifo: address of the fifo to be used
 * @buf: pointer to the storage buffer
 * @n: max. number of elements to get
 *
 * This macro get some data from the fifo and return the numbers of elements
 * copied.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_out(fifo, buf, n)                                                                         \
    __kfifo_uint_must_check_helper(({                                                                   \
        typeof((fifo) + 1) __tmp = (fifo);                                                              \
        typeof(__tmp->ptr) __buf = (buf);                                                               \
        unsigned long __n = (n);                                                                        \
        const size_t __recsize = sizeof(*__tmp->rectype);                                               \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                                        \
        (__recsize) ? __kfifo_out_r(__kfifo, __buf, __n, __recsize) : __kfifo_out(__kfifo, __buf, __n); \
    }))

/**
 * kfifo_out_spinlocked - get data from the fifo using a spinlock for locking
 * @fifo: address of the fifo to be used
 * @buf: pointer to the storage buffer
 * @n: max. number of elements to get
 * @lock: pointer to the spinlock to use for locking
 *
 * This macro get the data from the fifo and return the numbers of elements
 * copied.
 */
#define kfifo_out_spinlocked(fifo, buf, n, lock) \
    __kfifo_uint_must_check_helper(({            \
        unsigned long __flags;                   \
        unsigned int __ret;                      \
        spin_lock_irqsave(lock, __flags);        \
        __ret = kfifo_out(fifo, buf, n);         \
        spin_unlock_irqrestore(lock, __flags);   \
        __ret;                                   \
    }))

/**
 * kfifo_out_spinlocked_noirqsave - get data from the fifo using a spinlock
 * for locking, don't disable interrupts
 * @fifo: address of the fifo to be used
 * @buf: pointer to the storage buffer
 * @n: max. number of elements to get
 * @lock: pointer to the spinlock to use for locking
 *
 * This is a variant of kfifo_out_spinlocked() which uses spin_lock/unlock()
 * for locking and doesn't disable interrupts.
 */
#define kfifo_out_spinlocked_noirqsave(fifo, buf, n, lock) \
    __kfifo_uint_must_check_helper(({                      \
        unsigned int __ret;                                \
        spin_lock(lock);                                   \
        __ret = kfifo_out(fifo, buf, n);                   \
        spin_unlock(lock);                                 \
        __ret;                                             \
    }))

/* alias for kfifo_out_spinlocked, will be removed in a future release */
#define kfifo_out_locked(fifo, buf, n, lock) kfifo_out_spinlocked(fifo, buf, n, lock)

/**
 * kfifo_from_user - puts some data from user space into the fifo
 * @fifo: address of the fifo to be used
 * @from: pointer to the data to be added
 * @len: the length of the data to be added
 * @copied: pointer to output variable to store the number of copied bytes
 *
 * This macro copies at most @len bytes from the @from into the
 * fifo, depending of the available space and returns -EFAULT/0.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_from_user(fifo, from, len, copied)                                       \
    __kfifo_uint_must_check_helper(({                                                  \
        typeof((fifo) + 1) __tmp = (fifo);                                             \
        const void __user *__from = (from);                                            \
        unsigned int __len = (len);                                                    \
        unsigned int *__copied = (copied);                                             \
        const size_t __recsize = sizeof(*__tmp->rectype);                              \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                       \
        (__recsize) ? __kfifo_from_user_r(__kfifo, __from, __len, __copied, __recsize) \
                    : __kfifo_from_user(__kfifo, __from, __len, __copied);             \
    }))

/**
 * kfifo_to_user - copies data from the fifo into user space
 * @fifo: address of the fifo to be used
 * @to: where the data must be copied
 * @len: the size of the destination buffer
 * @copied: pointer to output variable to store the number of copied bytes
 *
 * This macro copies at most @len bytes from the fifo into the
 * @to buffer and returns -EFAULT/0.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_to_user(fifo, to, len, copied)                                       \
    __kfifo_uint_must_check_helper(({                                              \
        typeof((fifo) + 1) __tmp = (fifo);                                         \
        void __user *__to = (to);                                                  \
        unsigned int __len = (len);                                                \
        unsigned int *__copied = (copied);                                         \
        const size_t __recsize = sizeof(*__tmp->rectype);                          \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                   \
        (__recsize) ? __kfifo_to_user_r(__kfifo, __to, __len, __copied, __recsize) \
                    : __kfifo_to_user(__kfifo, __to, __len, __copied);             \
    }))

/**
 * kfifo_dma_in_prepare - setup a scatterlist for DMA input
 * @fifo: address of the fifo to be used
 * @sgl: pointer to the scatterlist array
 * @nents: number of entries in the scatterlist array
 * @len: number of elements to transfer
 *
 * This macro fills a scatterlist for DMA input.
 * It returns the number entries in the scatterlist array.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macros.
 */
#define kfifo_dma_in_prepare(fifo, sgl, nents, len)                                       \
    ({                                                                                    \
        typeof((fifo) + 1) __tmp = (fifo);                                                \
        struct scatterlist *__sgl = (sgl);                                                \
        int __nents = (nents);                                                            \
        unsigned int __len = (len);                                                       \
        const size_t __recsize = sizeof(*__tmp->rectype);                                 \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                          \
        (__recsize) ? __kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) \
                    : __kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len);             \
    })

/**
 * kfifo_dma_in_finish - finish a DMA IN operation
 * @fifo: address of the fifo to be used
 * @len: number of bytes to received
 *
 * This macro finish a DMA IN operation. The in counter will be updated by
 * the len parameter. No error checking will be done.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macros.
 */
#define kfifo_dma_in_finish(fifo, len)                          \
    (void)({                                                    \
        typeof((fifo) + 1) __tmp = (fifo);                      \
        unsigned int __len = (len);                             \
        const size_t __recsize = sizeof(*__tmp->rectype);       \
        struct __kfifo *__kfifo = &__tmp->kfifo;                \
        if (__recsize)                                          \
            __kfifo_dma_in_finish_r(__kfifo, __len, __recsize); \
        else                                                    \
            __kfifo->in += __len / sizeof(*__tmp->type);        \
    })

/**
 * kfifo_dma_out_prepare - setup a scatterlist for DMA output
 * @fifo: address of the fifo to be used
 * @sgl: pointer to the scatterlist array
 * @nents: number of entries in the scatterlist array
 * @len: number of elements to transfer
 *
 * This macro fills a scatterlist for DMA output which at most @len bytes
 * to transfer.
 * It returns the number entries in the scatterlist array.
 * A zero means there is no space available and the scatterlist is not filled.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macros.
 */
#define kfifo_dma_out_prepare(fifo, sgl, nents, len)                                       \
    ({                                                                                     \
        typeof((fifo) + 1) __tmp = (fifo);                                                 \
        struct scatterlist *__sgl = (sgl);                                                 \
        int __nents = (nents);                                                             \
        unsigned int __len = (len);                                                        \
        const size_t __recsize = sizeof(*__tmp->rectype);                                  \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                           \
        (__recsize) ? __kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) \
                    : __kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len);             \
    })

/**
 * kfifo_dma_out_finish - finish a DMA OUT operation
 * @fifo: address of the fifo to be used
 * @len: number of bytes transferred
 *
 * This macro finish a DMA OUT operation. The out counter will be updated by
 * the len parameter. No error checking will be done.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macros.
 */
#define kfifo_dma_out_finish(fifo, len)                   \
    (void)({                                              \
        typeof((fifo) + 1) __tmp = (fifo);                \
        unsigned int __len = (len);                       \
        const size_t __recsize = sizeof(*__tmp->rectype); \
        struct __kfifo *__kfifo = &__tmp->kfifo;          \
        if (__recsize)                                    \
            __kfifo_dma_out_finish_r(__kfifo, __recsize); \
        else                                              \
            __kfifo->out += __len / sizeof(*__tmp->type); \
    })

/**
 * kfifo_out_peek - gets some data from the fifo
 * @fifo: address of the fifo to be used
 * @buf: pointer to the storage buffer
 * @n: max. number of elements to get
 *
 * This macro get the data from the fifo and return the numbers of elements
 * copied. The data is not removed from the fifo.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these macro.
 */
#define kfifo_out_peek(fifo, buf, n)                                                                              \
    __kfifo_uint_must_check_helper(({                                                                             \
        typeof((fifo) + 1) __tmp = (fifo);                                                                        \
        typeof(__tmp->ptr) __buf = (buf);                                                                         \
        unsigned long __n = (n);                                                                                  \
        const size_t __recsize = sizeof(*__tmp->rectype);                                                         \
        struct __kfifo *__kfifo = &__tmp->kfifo;                                                                  \
        (__recsize) ? __kfifo_out_peek_r(__kfifo, __buf, __n, __recsize) : __kfifo_out_peek(__kfifo, __buf, __n); \
    }))

extern int __kfifo_init(struct __kfifo *fifo, void *buffer, unsigned int size, size_t esize);

extern unsigned int __kfifo_in(struct __kfifo *fifo, const void *buf, unsigned int len);

extern unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, unsigned int len);

extern unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize);

extern void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize);

extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf, unsigned int len, size_t recsize);

extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);

#ifdef __cplusplus
}
#endif

#endif
